Diffusing Void Model for Granular Flow

The gravitational flow pattern of granular media in a confined geometry is assumed to be caused by the upward motion of voids generated at the discharge orifices. The model describes some well known and unique features of granular flows such as the deformation of the free surface, the formation of dead zones, the flow around obstacles with its companion void regions and the formation of cascading zones. It also predicts an unexpected velocity profile in a flow expansion as well as the propagation of dilation waves whose scaling solutions are presented. These thin two-dimensional beds are also found to behave very differently from three-dimensional beds.